#while循环计算1_100整数的和
'''i=0
sum=1
while i<=100:
    sum+=1
    i+=1
    print(sum)'''


#for循环计算1--100整数的和

'''he=0
for j in range(1,101):
    he+=j
    print(he)'''
#for循环计算1--100偶数和
qiuHe=0
for w in range(1,101):
    if w%2==0:
        qiuHe+=w
print(qiuHe)